A subglacial lake 800 meters beneath ice, sealed from atmosphere for millennia. Microbes here survive in near-freezing darkness, using chemosynthesis powered by minerals weathered from bedrock.
An environment sealed from time
Beneath 800 meters (2,600 feet) of the West Antarctic Ice Sheet lies Subglacial Lake Whillans, a body of water completely cut off from the sunlit world. First identified in 2007 by glaciologist Helen Fricker, its existence was inferred from NASA satellite data that showed the ice surface mysteriously rising and falling. This indicated a dynamic body of water was filling and draining below.
Lake Whillans is a shallow reservoir, covering roughly 60 square kilometers (20 square miles) with a depth of only about 2 meters. It is part of a vast, interconnected system of channels and lakes hidden beneath the ice. The lake is not static; it undergoes fill-and-drain cycles that can last for years. These hydrologic events cause water to move between lakes, influencing the motion of the massive Whillans Ice Stream above it.
In January 2013, the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project achieved a major milestone. Using a specially designed hot-water drill equipped with filtration and sterilization systems to prevent contamination, researchers melted a borehole 30 centimeters in diameter through the ice sheet and reached the lake. For the first time, they collected clean water and sediment samples directly from this isolated environment. The water temperature was a frigid -0.5°C (-0.55°C minimum), kept liquid by the immense pressure of the ice above.
Life without light
The samples from Lake Whillans confirmed the presence of a metabolically active microbial community. Initial analysis revealed a diverse ecosystem with at least 3,900 different kinds of microorganisms, a mix of bacteria and archaea. Sunlight cannot penetrate the thick ice, so photosynthesis is impossible. Instead, life in Lake Whillans is powered by chemosynthesis.
These microbes act as the foundation of the ecosystem, deriving energy from chemical reactions with minerals and nutrients contained within the bedrock and sediment. The ecosystem appears to be based on the oxidation of various compounds, including those of ammonia, iron, and sulfur. Organisms related to Thiobacillus, Sideroxydans, and Candidatus Nitrotoga are abundant, pointing to the importance of sulfur, iron, and nitrogen cycling. Methane cycling also appears to occur, with methanogenic taxa found deep in the sediment.
The water chemistry is dominated by the weathering of silicate minerals from the underlying rock, with only a minor influence from ancient seawater. The sediments themselves are thought to have been laid down at least 120,000 years ago, providing a long-term source of the chemicals that fuel this dark biosphere. Studying this ecosystem shows life might survive in other extreme, sunless environments on Earth and potentially on other icy moons in our solar system, such as Europa or Enceladus.
💡Fun Facts
The water in Lake Whillans is kept from freezing by the immense pressure of the 800 meters of ice above it, which lowers the freezing point to about -0.5°C.
The lake is part of an active plumbing system; it fills with meltwater and periodically drains over years, causing the ice sheet surface above to rise and fall.
The custom hot-water drill used by the WISSARD project was designed to be exceptionally clean, filtering and sterilizing the water to avoid contaminating the pristine subglacial environment.
The discovery of this ecosystem was first made possible not by drilling, but by observing the ice surface move up and down with satellite laser altimetry.